Wire centering device for a wire stripper

ABSTRACT

A wire stripper capable of automatically grasping a coated wire, cutting the coating with cutters, rotating the cutters and stripping the cut coating away with only one electric motor. The wire stripper is provided with a reversible main spindle which is supported on a machine frame and allowed to slide crosswise so as to enable gripping operation of the grippers as well as nipping and cutting operation of the cutters. The main spindle is provided with a lead-screw shaft with which a nut block is coupled so that the lead-screw shaft advances by forward rotation of the main spindle to close the grippers and the cutters as well as to rotate the cutters. The nut block is then moved backward by the lead screw of the lead-screw shaft after the main spindle has stopped advancing and the cutters are then withdrawn to strip the cut coating away from the core.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention concerns a wire stripper for automatically stripping thecoating off the end of a coated wire in a required length. The inventionfurther concerns a centering device for the wire stripper.

2. Discussion of the Prior Art

Various wire strippers have been made available which serve forstripping the coating off the end of a coated wire and exposing the corein a required length.

With such conventional wire strippers, in general, a coated wire isinserted into a machine and gripped at the end from both sides bygrippers, and is nipped at the same time by cutters from both sideswhere its coating is to be cut. The cutters cut only the coating andstrip the coating away from the wire end while being withdrawn.

Cutters and grippers of such conventional wire strippers are opened andclosed by reciprocating motion of a cutter/gripper operating element bymeans of an pneumatic cylinder (or hydraulic cylinder) or throughoperation of cutter/gripper operating cams by means of an electricmotor.

To mention some of the problems concerning conventional wire strippers,the pneumatic or hydraulic cylinder necessitates a compressor or ahydraulic unit, respectively, in addition to the wire stripper, whichremarkably restricts the place where such wire stripper can be used incombination with such equipment. Furthermore, the compressor causes highexhaustion noise and may adversely affect the mechanism due to moisturecontained in the air.

The variation using cams requires large decelerator and large componentsincluding a coupling because an electric motor has to be used separatelyfor each motion, or motor rotation has to be transmitted to the cam onlyafter substantial deceleration, which results in large and expensivewire strippers.

SUMMARY OF THE INVENTION

The present invention has the object of providing a remarkably small,quiet and inexpensive wire stripper without restrictions about locationof use because gripping of wire and stripping of coating can beperformed by means of a conventional reversible motor. A main spindle issupported on machine frame, being allowed to slide longitudinally, andis reversible in rotation by means of only one motor and is providedwith a lead-screw shaft coupled with a nut block. The lead-screw shaftmoves forward to the nut block by forward rotation of the main spindleto close the grippers and the cutters and at the same time to rotate thecutters. The nut block moves backward to retract the cutters after themain spindle has stopped to advance.

The invention further has the object of providing a wire centeringdevice for the wire stripper.

The invention aims at providing an inexpensive compact wire strippercapable of automatically grasping a coated wire, cutting the coatingwith cutters, rotating the cutters and stripping the cut coating away bymeans of only one electric motor. This is accomplished in the presentinvention as follows: A wire stripper according to the invention isprovided with a reversible main spindle which is supported on machineframe and allowed to slide crosswise so as to enable gripping operationof the grippers as well as nipping and cutting operation of the cutters.The main spindle is provided with lead-screwed shaft with which a nutblock is coupled so that the lead-screwed shaft advances by forwardrotation of the main spindle to close the grippers and the cutters aswell as to rotate the cutters. The nut block is then moved backward bythe lead screw of the lead-screwed shaft after the main spindle hasstopped to advance and the cutters are then withdrawn to strip the cutcoating away from the core.

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of the disclosure. For a better understanding of the invention, itsoperating advantages, and specific objects attained by its use,reference should be had to the drawing and descriptive matter in whichthere are illustrated and described preferred embodiments of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: is a perspective view of a working form of wire stripperaccording to the invention;

FIG. 2: is a longitudinal section A—A of FIG. 3;

FIG. 2A is a more detailed view similar to FIG. 2 of the wire stripper;

FIG. 2B is a view B in FIG. 2A;

FIG. 2C is a detailed view of the grippers;

FIG. 3: is a horizontal section of FIG. 1;

FIG. 4: is a sketch showing cutter arm operation;

FIG. 5: is a section B—B according to FIG. 4;

FIG. 6: is a partial view of the cutter according to FIG. 4;

FIGS. 7A and 7B: are explanatory sketches of cutter function;

FIGS. 8A To 8C: are disassembly sketches of the cutter structure;

FIG. 9: is a top view of one embodiment of the cutter;

FIGS. 10A and 10B: show a front view of the cutter; and

FIGS. 11A and 11B: show a cutter holder with a pusher plate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows the appearance of a working form of a wire stripperaccording to the invention. FIG. 2 shows its longitudinal section(corresponding to section A—A of FIG. 3) and FIG. 3 shows its horizontalsection. In the description below, the left side in FIGS. 1 through 3where wire comes in is referred to as “front side” and the right side as“rear side”.

As shown in FIG. 2, a main spindle 3 is supported in a lower positionbetween side walls 2 at the front end and the rear end in thelongitudinal direction of machine frame 1, so that the spindle 3 canrotate and at the same time slide axially. Two gripper shafts 4 areprovided over the main spindle 3 parallel to each other. A cutter shaft5 is located above and between the gripper shafts 4.

The rear end of the main spindle 3 is formed as a spline shaft 6 (orkey) with a required length. A toothed pulley 9 is fitted on the splineshaft 6 to receive rotation via a timing belt 8 from a conventionalreversible motor 7 (FIG. 3) such as an induction motor (single phase), acooled reversible motor, etc. mounted on the machine frame 1 so as totransmit rotation of the motor 7 to the main spindle 3.

The intermediate portion of the main spindle 3 is formed as alead-screwed shaft 10, on which a nut block 11 is fitted to move forwardor backward axially in accordance with the rotating direction of themain spindle 3.

A first cam 12 tapering off to the front side is fixed co-axially to themain spindle 3 between the spline shaft and the lead-screwed shaft 10. Asecond cam 13 tapering off to the front side is fitted in front of thenut block 11 and allowed to slide. A compression spring 14 in the formof a coil is inserted between the thicker end of second conical cam 13and the nut block 11. The lead-screwed shaft 10 and the nut block 11 maybe of ball screw specification.

At the front end of the main spindle 3 protruding from the side wall 2of the machine frame 1, a positioning element 16 is fitted to moveforward and backward by screw-through rotation of a knob 15 a of aninfeed adjusting mechanism 15 for adjustment of infeed to the coating ofwire W. A thrust bearing 17 is provided on the inner end of thepositioning element 16 to bring it into contact with the front end ofthe second conical cam 13.

A cylindrical part 18 on the tip of the second conical cam 13 isprovided with an axial slot 19, into which a pin 20, fixed to the mainspindle 3, is fitted so that advance of the main spindle 3 is allowed bythe length of the slot 19 after the front end of the second conical cam13 has come in contact with the thrust bearing 17 at the inner end ofthe positioning clement 16.

A base 21 a of grippers 21, 21 is fixed to the front end of the grippershafts 4, respectively, while the upper ends of arms 22, are fixed andsuspended near the rear ends of the gripper shafts 4, respectively. Camrollers 23, are attached to the lower end of arms 22 so that they canrotate on a horizontal plane. The cam rollers 23 are kept in contactwith the peripheral face of the first conical cam 12 and pushed by itsconical periphery when it moves forward to rotate the gripper shafts 4in opposite directions to each other. The grippers 21, close (wiregripped) when the first conical cam 12 moves forward, while they areopened in case of backward movement.

The front end of the cutter shaft 5 is located on the side wall 2 at thefront end of machine frame 1. A holder 24 fixed to the front end of thecutter shaft 5 bears cutter arms 25, symmetrically about the axis of thecutter arm 25 by means of shafts 26, located a little behind the middlepoints of the cutter arms 25. The cutter arms 25, are provided at thefront end with cutters 27 that face each other and with cam rollers 28at the rear end.

A third conical cam 30 is sliding-fitted to the cutter shaft 5. Acompression spring 31 is inserted between the cam 30 and the holder 24.

A spline shaft 32 (or key) is fitted on the rear end of the cutter shaft5, to which a sliding cylinder 33 is sliding-fitted. A female-screw part33 a at the rear end of the sliding cylinder 33 is connected to alead-screw part 34 fixed to the side wall 2.

The second conical cam 13 is provided with oscillating members 36 (onlyone of them shown in FIG. 2) on both sides which are supported on themachine frame 1 in erected position by a spring on the lower end so thatthey can oscillate on the shafts 35. A cam roller 38 on a vertical shaft37 of the oscillating member 36 is designed to come in contact with theperipheral face of the second conical cam 13.

On the other hand, a shaft 40 vertical to a supporting member 39substantially integrated to the nut block 11 is supported so that it canrotate freely. A roller 42 on the tip of the lever 41, whose base end isfixed to the lower end of the shaft 40, is in contact with the outerface of the oscillating member 36 at a point near the upper end. Aroller 44 on the tip of a lever 43, whose base end is fixed to the upperend of the shaft 40, is in contact with the rear end of the thirdconical cam 30. The roller 42 of the lever 41 is always kept in contactwith the oscillating member 36 by the action of the compression spring31. When the second conical cam 13 moves forward, the oscillating member36 is pushed outward so that the roller 44 of the lever 43 moves thethird conical cam 30 forward against the action of the compressionspring 31.

A cylindrical member 46 having flanges 45, on its front and rear ends isprovided at the front end of the first conical cam 12. Rollers 49, onthe tip of a lower lever 48, which is reverse-C-shaped if seen from thelateral side and fixed to a shaft 47 supported on the machine frame 1and allowed to rotate, are put between the flanges 45, of thecylindrical member 46 with axial play. Rollers 51 on the tip of an upperlever 50, which is reverse-C-shaped if seen from the lateral side andfixed to the upper part of the shaft 47, are fitted into a peripheralgroove 52 formed on the sliding cylinder 33 in peripheral direction.When the rollers 49 of the lower lever 48 are pushed by the rear flange45 of the cylindrical member 46, the upper lever 50 oscillates to movethe sliding cylinder 33 forward via its rollers 51, which in turn isconnected with the lead-screw part 34 to transmit rotation to the cuttershaft 5 through the spline shaft 32 to complete an interlockingmechanism.

A brake unit 53 is provided between the nut block 11 and the rear sidewall 2 of the machine frame 1 to decelerate return (backward movement)of the nut block 11. The brake unit 53 is coupled with a plate 57 on thenut block side by means of a shaft 56 inserted into a horizontal slot 55of a base 54 fixed to the side wall 2 and exerts braking action byfriction due to the force of a spring, not shown in the figure, via theshaft 56. Resistance to return of the nut block 11 is converted intogripping force of the grippers 21 which grip the wire strongly.

The timing of movement of the first and second conical cams 12, 13 isdesigned so that the main spindle 3 advances by lead screw on itslead-screw shaft 10 while the nut block is kept fixed during forwardrotation of main spindle 3. The first conical cam 12 closes the cutters27, the second conical cam 13 moves forward to close the grippers 21,and the nut block 11 moves backward against the resistance of the brakeunit 53 by reaction force caused when the second conical cam 13 stops.This resistance is converted into a force to close the grippers 21,strongly and then the cutters 27 move backward as a result of retractionof the nut block 11 to strip the coating away from core.

The cutters 27 comprise two cutting edges (first cutting element 27 a,second cutting element 27 b) respectively as shown in FIG. 6, FIGS. 7(A), (B) and FIGS. 8 (A), (B). A cutting edge 27 c of the first cuttingelement 27 a of the one cutter arm 25 and a cutting edge 27 c of thefirst cutting element 27 a of the other cutter arm 25 have the sameinclination so that they become parallel to each other in butt position.Cutting edges 27 d, 27 d of the second cutting elements 27 b, to belapped over the first cutting elements 27 a have the same inclination asthat of the cutting edges 27 c of the first cutting elements 27 a, butin reverse direction. Thus, the cutting edges 27 c, 27 d of the firstand second cutting elements 27 a, 27 b present an obtuse V shape if seenfrom the front side. The first and second cutting elements 27 a, 27 bare thus fed in to cut the wire coating when closed in lapped position,according to wire outer diameter as shown in FIGS. 7 (A), (B).

The cutting elements 27 a, 27 b of the cutters 27 are mounted to thecutter arm 25 with a spacer 27 e (approx. 0.2 to 0.3 mm thick) insertedbetween them so as to prevent collision of the cutter edges 27 c, 27 dwith each other when they pass each other. As a result of this, theV-forming cutting edges are apart from others so that interference ofcutting edges with each other is prevented when the cutting edges of theupper and lower cutters 27 are fed in to engage while tracing a circulararc.

The knob 15 a of the infeed adjusting mechanism 15 is provided on itsperipheral face with graduations 58 in {fraction (5/100)} mm. By turningthe knob 15 a, the positioning member 16 fitted on the peripheral screwof a shaft 15 b of the knob 15 a, moves forward or backward to adjustthe position of its inner end (thrust bearing 17).

In FIG. 3, a sensor 59 is shown which is used for setting a startingposition operated by the nut block 11 and a sensor 60 is shown fordetecting completed stripping and giving a reversing command to themotor 7.

The effects of the working form are described in the following. The knob15 a of the infeed adjusting mechanism 15 is turned first in order toset infeed in accordance with the diameter of the wire to be handledreferring to the graduations 58. Then, the coated wire W is put betweenthe grippers 21 and held in position where the required stripping lengthof coating is ensured. A switch, not indicated in the figure, is turnedon to start motor 7. The motor 7 operates in forward direction and themain spindle 3 rotates in the forward direction.

At the beginning of forward rotation of the main spindle 3, the nutblock 11 is kept fixed by resistance of the brake unit 53 so that themain spindle 3 advances because of the coupling between its lead-screwshaft 10 and the nut block 11.

The first conical cam 12 then pushes the rollers 23 outward to oscillatethe arms 22. The gripper shafts 4 fixed to the arms 22 rotaterespectively to close grippers 21 on their tip to grip the coated wire.

At the same time, the second conical cam 13 pushes the rollers 38 tooscillate the oscillating members 36 outward by using the shafts 35 assupporting point. Oscillation of the oscillating members 36 istransmitted via the roller 42, the lever 41, the shaft 40, the lever 43and the roller 44 to push forward the third conical cam 30.

Forward movement of the third conical cam 30 pushes outward the rollers28 of the cutter arms 25 which turn around the shafts 26 respectively toclose the cutters 27 on the tip to cut the coating of the coated wire Wup to a specified depth.

At this moment, the rear flange 45 of the cylindrical member 46 on thetip of the first conical cam 12 comes in contact with the rollers 49 ofthe lower lever 48 and pushes them so that the lower lever 48 turnsaround the shaft 47. This turning movement is transmitted via the shaft47 to the upper lever 50 whose rollers 51 move the sliding cylinder 33forward.

Because the lead-screw part 34 on the machine frame side is coupled withthe female-screw part 33 a, the sliding cylinder 33 rotates during itsforward movement. The cutter shaft 5 connected to the sliding cylinder33 by the spline shaft 32 rotates so that the cutters 27 turn whilebeing fed in to the coated wire W to cut the coating uniformly over theentire periphery.

The pin 20 of the main spindle 3 advances further by the length of theslot 19 of the cylindrical part 18 after the cylindrical part 18 on thetip of the second conical cam 13 has come in contact with the inner endof the positioning member 16 and the second conical cam 13 has stopped.Forward movement corresponding to this stroke of the pin 20 serves asthe rotation stroke for the sliding cylinder 33.

When the pin 20 has come in contact with the front end of the slot 19,the main spindle 3 is no longer able to advance. Then, the nut block 11begins to move backward by lead screw on the rotating main spindle 3 toretract the cutter shaft 5 together with the coating having been cut bythe cutters 27. The third conical cam 30 does not move backward at thismoment because it is blocked at the rear end by the rollers 44 of thelevers 43, so that the cutters 27 are held in nipping position and movebackward to strip the cut coating away from the core.

When the nut block 11 has been detected by the sensor 60 for givingreversing command, the motor 7 operates in reverse direction to reversethe main spindle 3, which then returns first by lead screw on itslead-screw shaft 10. As a result of this, the grippers 21 having beenkept in a closed position are opened by a procedure reverse to the aboveto release the coated wire W. As the second conical cam 13 movesbackward, the oscillating members 36 return to a vertical position andthe rollers 44 of the levers 43 return as well. Then, the lower cutterarm 25 lowers while oscillating on the cutter side and thus cutters 27come apart from each other. The nut block 11 moves forward to theinitial position (as shown in FIGS. 2 and 3) by the action of thelead-screw shaft 10. The sensor 59 detects this and stops the motor 7 tocomplete the process.

A non-reversible motor may also be used instead of a reversible motor ifthe main spindle rotation can be changed by means of a clutch.Notwithstanding the working form as described above where the cuttershaft 5 is rotated by the lead screw 34 through the interlockingmechanism in combination with the movement of the first conical cam 12,a motor may also be provided separately for rotating the cutter shaft 5and may be set to operate at a specified moment to rotate the cuttershaft 5.

In another embodiment one of both cutting elements 27 a and 27 b isenabled to move forward and backward in a wire nipping direction andforms part of a centering device. The edge of the movable cuttingelement is flattened so as to ensure more positive centering by movementof the cutting element at wire nipping operation in accordance with wirediameter and infeed.

A concrete working form for this is shown in FIGS. 9 through 11 bytaking one of the cutters 27 as a representative example. First andsecond cutting elements 271, 272 are attached, with the spacer 27 ebetween them, to the front end of a cutter holder 61 on the tip of thecutter arm 25 by means of a lap screw 62. The cutting element on outerside of the two, namely cutting element 271, is made movable in the wirenipping direction through its mounting hole 63 formed as a slotextending in the wire nipping direction, and is provided, with aflattened edge 271 a. The cutter holder 61 is provided on its back sidewith a pushing element 64 which pushes the said cutting element 271 atthe end opposite to edge 271 a. In the illustrated example, a pusherplate 66 supported at its intermediate portion by a shaft 65 as shown inFIGS. 11 (A), (B) is provided on the cutter holder 61. The front end 66a of the pusher plate 66 is in contact with the outer end of the cuttingelement 271. The tip of a compression spring 68, approximately half ofwhich is fitted in a supporting hole 67 formed in the cutter holder 61,is in contact with the opposite end of the pusher plate 66. Thecompression spring 68 pushes the rear end of the pusher plate 66 so thatthe front end 66 a of the pusher plate 66 pushes the cutting element 271into the direction of advance of the edge 271 a. Means for supplying thepushing force is not limited to the compression spring 68, but may beany other means that pushes the cutting element 271 in the direction ofadvance of the edge, such as a wire spring, a leaf spring, etc. With thecutter structure, infeed is determined by the cutting edge 272 a of thefixed cutting element 272 a at the moment when the cutting elements 271,272 of both cutters nip the wire W while the edge 271 a of the movablecutting element 271 comes in contact with the outer face of the wire Was shown in FIG. 10 (A) and then retracts in accordance with infeed L asshown in FIG. 10 (B) against the force given by the compression spring68. Thus, the wire W regardless of its diameter is always brought to thecenter between the cutting edges of the cutting elements 271, 272 byboth cutters 27 so that the coating can be cut to a uniform depth overthe entire periphery of the wire W by turning the cutters on the basisof ensured centering of the wire W. Notwithstanding the working formwhere the outer cutting element 271 is made movable, it is naturallypossible to make the inner cutting element 272 movable and to fix theouter cutting element 27.

The invention is not limited by the embodiments described above whichare presented as examples only but can be modified in various wayswithin the scope of protection defined by the appended patent claims.

I claim:
 1. A wire centering device for a wire stripper, comprising: twocutters arranged to oppose one another, each of the cutters includingtwo cutting elements arranged adjacent one another, at least one of thecutting elements being movable in a wire nipping direction, the onecutting element having a flattened edge, and means for pushing the onecutting element in the wire nipping direction, the one cutting elementbeing configured to retract against pushing by the pushing means uponengagement with a wire thereby positively centering the wire.
 2. A wirecentering device according to claim 1, wherein both the cutting elementshave a cutting edge, the cutting edges of the respective cuttingelements each having an equal and opposite inclination so that thecutting edges of the cutting elements together form an obtuse V-shape asseen from a front side of the cutting elements.
 3. A centering deviceaccording to claims 2, and further comprising a spacer arranged betweenthe two cutting elements.
 4. A wire centering device according to claim2, wherein each of the cutting elements has a through hole.
 5. A wirecentering device according to claim 2, and further comprising a holderhaving a front side and a back side, the cutting elements being arrangedat a front side of the holder, the pushing means including a levermember having a front end connected to the movable cutting element withthe flattened cutting edge, and a rear end, the lever member beingpivotably connected to the holder at a point between the front end andback end of the lever.
 6. A wire centering device according to claim 5,wherein the pushing means further includes spring means acting on therear end region of the lever member so as to pivot the lever whereby thecutting element with the flattened cutting edge is moved.
 7. A wirecentering device according to claim 4, wherein the spring means is acompression spring mounted in the holder.
 8. A wire centering deviceaccording to claim 4, wherein the spring means includes a wire spring.9. A wire centering device according to claim 4, wherein the springmeans includes a leaf spring.